In a prior-art hemming device (U.S. Pat. No. 5,150,508), all drives consist of hydraulic cylinders. Since a plurality of hydraulic cylinders, which must all be actuated simultaneously and uniformly in terms of their stroke and their dynamic effect, are provided not only for the hemming stroke but also for the displacing stroke, the control of these drives can be problematic. To keep the number of the respective groups of hydraulic cylinders low and to guarantee, at the same time, a reliable support of these hydraulic cylinders, the components involved in this, especially the moving components, must have relatively large masses.